Safety switch for internal combustion engines



Sept. 17 1963 E. M. WARREN 3,104,301

SAFETY SWITCH FOR INTERNAL COMBUSTION ENGINES Filed Feb. 16, 1961 s Sheets-Sheet 1 ATTORNEYS IN VENTOR EZL MY Z Jrrem Sept. 17, 1963 E. M. WARREN 3,104,301

SAFETY swncn FOR INTERNAL COMBUSTION ENGINES Filed Feb. 16, 1961 s Sheets-Sheet 2 BY W ATTORNEYS Sept. 17, 1963 E. M. WARREN 3,104,301

SAFETY SWITCH FOR INTERNAL COMBUSTION ENGINES Filed Feb. 16, 1961 5 Sheets-Sheet 5 INVENTOR 2125/ M gl drrew ATTORNEYS 3,104,301 SAFETY SWITCH FOR INTERNAL COMBUSTION ENGINES Estel M. Warren, 311 Elizabeth St., Clinton, N.C. Filed Feb. 16, 1961, Ser. No. 89,759 8 Claims. (Ell. 200-161) This invention relates to the control of electrical circuits and more particularly to a master battery switch for internal combustion engines having an electric starter circult and in many cases a primary ignition circuit. While the device of this invention is primarily intended to eliminate fire hazards in vehicles resulting from short circuits, the device also provides protection against unauthorized operation of an internal combustion engine and eliminates battery drain due to electrical leakage in the various wire circuits.

Numerous types of safety devices have heretofore been proposed and utilized for preventing unauthorized use of automobiles or unauthorized operation of internal combustion engines, but in many cases it was possible to avoid the effect of such safety devices by utilizing an auxiliary battery wired directly to the starter circuit or by by-passing the ignition switch with a suitable conductor. Also, since the electrical systems in automobiles vary, in that certain automobiles are provided with a grounded electrical system while others are provided with an ungrounded system, the previous safety devices did not take account of this fact and consequently, considerable difiiculty was some times experienced in proper installation of such safety devices.

It is accordingly an object of the invention to provide a safety switch for internal combustion engines which may be conveniently installed in an automobile or in connection with other types of internal combustion engines without requiring modification other than reconnecting of certain wires of the starter circuit.

A further object of the invention is the provision of a safety switch for internal combustion engines having an electric starter circuit and a primary ignition circuit, which device may be conveniently mounted and utilized in connection with either a grounded or an ungrounded electrical system.

A still further object of the invention is the provision of a safety switch for internal combustion engines having an electric starter circuit and a primary ignition circuit and in which a simple manipulation of the switch from a remote point serves to render the electric starter circuit, as well as the primary ignition circuit inoperative, thereby preventing unauthorized use of the engine.

Another object of the invention is the provision of a safety switch for internal combustion engine having an electric starter circuit and a primary ignition circuit, which switch by actuation from a remote point serves to prevent operation of the engine, even though the normal ignition switch of the engine may be bypassed by an electrical conductor.

A further object of the invention is the provision of a safety switch for internal combustion engines having an electric starter circuit and a primary ignition circuit, which switch renders the starter circuit inoperative and thereby prevents unauthorized use of the engine even though the ignition circuit may in some way be rendered operative.

A still further object of the invention is the provision of a safety switch for internal combustion engines which may be conveniently and economically manufactured from readily available material and which may be conveniently installed in an accessible place in a motor vehicle or adjacent an internal combustion engine and in which the switch may be operated from a remote point, such as the instrument panel of an automobile.

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Another object of the invention is the provision of a safety switch for internal combustion engines having an electric starter circuit and a primary ignition circuit and incorporating novel means for providing a low resistance switch in the electric starter circuit thereby maintaining voltage drop to a minimum.

A still further object of the invention is the provision of a safety switch for internal combustion engines incorporating novel means which as the result of a simple manual operation adapts the switch for use on a grounded or ungrounded electrical system.

Another object of the invention is the provision of a safety switch for internal combustion engines which may be utilized to ground the generator output thereby preventing damage to the generator and associated electrical equipment.

A further object of the invention is the provision of a safety switch for internal combustion engines in which the switch is vapor proof thereby materially reducing fire hazard.

A still further object of the invention is the provision of a safety switch which may be utilized in connection with an internal combustion engine having electrical ignition or with a diesel type engine.

Further objects and advantages of the invention will be apparent from the following description taken in conjunction with the accompanying drawing wherein:

FIG. 1 is a side elevational view of a safety switch constructed in accordance with this invention and showing in dotted lines the position of the switch elements to render the electric starter and primary ignition circuits inoperative;

FIG. 2 a top plan view of the switch shown in FIG. 1;

FIG. 3 a rear elevational view of the switch shown in FIG. 1 and with parts in the same relative positions;

FIG. 4 a front elevational View of the switch housing with the cover plate removed and with parts broken away and in section for greater clarity and showing the manner of mounting the various contacts and terminals;

FIG. 5 a front elevational view with parts broken away and in section for greater clarity and showing the slidable block forming the flexible operating member of the switch of this invention;

FIG. 6 an end elevational view looking from the left of FIG. 5 and showing the structure of the bridging or switch member carried by the block shown in FIG. 5;

FIG. 7 a side elevational view looking from the right hand side of FIG. 5;

FIG. 8 an elevational view with parts broken away and in section for greater clarity and showing the cover plate for the switch housing;

FIG. 9 a front elevational view similar to FIG. 1 but with the cover plate removed to show the position of the parts for rendering the starter and ignition circuits of the internal combustion engine inoperative; and

FIG. 10 a view similar to FIG. 9, but showing the parts in position to permit operation of the starter and ignition circuit.

With continued reference to the drawing, there is shown a master battery or safety switch for internal combustion engines constructed in accordance with this invention which may well comprise a generally rectangular housing 10 of insulating material and \as best shown in FIGS. 4, 9 and 10, the housing 10 may be provided with a generally rectangular recess 11. A pair of spaced contacts 12 and 13 are disposed in the recess 11 atone end thereof and the contact 12 may be secured in place by a screw threaded member 14 extending therethrough and through the end wall 15 of the body 10, the screw threaded member and the contact '12 being secured in position by a nut 16 threadedly received on the outer end of the screw threaded member 12. A'second nut 17 may also be provided on the screw threaded member 14 in order to facilitate attachment of an electrical conductor thereto. in a similar manner, the contact 13 may be secured in place in the recess 11 of the housing by means of a screw threaded member 18 projecting therethrough and through the end wall .15 of the housing 10 there being a nut 19 received on the outer end of the screw threaded member 18 to securely hold the contact 13 in position. A second nut 20 may be provided on the screw threaded member 18 in order to facilitate attachment of an electrical conductor thereto. As shown in FIGS. 4, 9 and 10 they inner end of the screw threaded member 18 is provided with an enlargement 21 having a screw threaded aperture 22 therein, the purpose of which will be later described. It should be noted that the inner ends of the contacts 12 and 13 are provided with curved opposed portions 23 and 24 which cooperate with a bridging or switch member in a manner to be later described. A strip of insulating material 25 is secured to the screw threaded members 14 and 18 is provided with a looped portion 26 disposed between the outer ends of the screw threaded members 14 and 18 in order to prevent a possible short circuit between conductors attached to the terminals provided by the screw threaded members 14 and 18.

At the opposite end of the housing 10 from the contacts 12 and 13 there is provided a fixed contact 27 projecting into the recess 11 and the contact 27 may, if desired, constitute the inner end of a screw threaded member 28 which extends through the end wall 29 of the housing 10 and is secured in place thereon by a nut 30 received on the screw threaded member 28. A second nut 31 may also he received on the screw threaded member 28 to provide terminal means for attaching a conductor thereto. A resilient movable contact 31. is disposed in the recess 11 of the housing 10 and the rnovable contact 31 is provided with an offset portion 32 received in :a recess 33 of the end wall 29 and a screw threaded member 34 engages the ofiset portion 32 of the contact 31 to hold the same in position. The inner end 35 of the movable contact 31 is disposed in alignment with the fixed contact 27 and the contact 31 may move into or out of engagement with the fixed contact 27 in a manner and for a purpose to be later described.

A mounting bracket 36 is secured to the sidewall 37 of the body 10 by screw threaded fastening means or the like 38 and as shown in FIGS. 2 and 4, the mounting bracket 36 may be provided with an outwardly extending end portion 39 provided with an aperture 41 for facilitating mounting of the switch of this invention at a convenient location in a motor vehicle or adjacent an internal combustion engine to be controlled thereby. It is to be noted, that the screw threaded member 34 securing the movable contact 31 in place is provided with a head member 41 engaging the mounting bracket 36 to provide an electrical connection between such bracket and the movable contact 31 and furthermore, a removable screw threaded member 42 having a head 43, may be threadedly engaged in the recess 22 of the enlarged portion 21 on the inner end of the screw threaded member 18 with the head 43 engaging the mounting bracket 36 to provide an electrical connection between such bracket and the terminal provided by the screw threaded member 18. In certain instances, it may .be desirable to remove the screw threaded member 42 and replace the same with a short screw threaded member which is not received in the recess 22 of the enlarged portion 21 in order to eliminate an electrical connection between the bracket 36 and the terminal provided by the screw threaded member .18.

A generally rectangular block 44 of insulating material is slidably mounted in the recess 11 of the housing 10 and as clearly shown in FIGS. 9 and 10, the block 44 is movable between the end walls 15 and 29' of the housing 10. A tapered bridging or switch member 45 is provided with a tang 46 received in an aperture 47 in the wall 48 of the block 44 and a pin 49 extends through the wall 48 of the block 44 and through an aperture in the tang 46 to loosely mount the bridging or switch member on the block 44. The bridging or switch member 45 may pivot about the pin 49 to an extent limited by the size of the aperture 47 and likewise, considerable play will be provided between the pin 49 and the aperture in the tang 46 in order to, in effect, provide a flouting mounting for the bridging or switch member 45. As best shown in FIGS. 5 and 6, the bridging or switch member 45 is provided with opposed tapered surfaces 59 and 51, it being noted that the tapered surface 5% is provided with spaced ribs 52 and 53 and the surface 51 with spaced ribs 54 and 55. As best shown in FIG. 10, the bridging or switch member 45 is received between the curved inner ends of the contacts 23 and 24 with the ribs 52 and 53 engaging the contact 24 and the ribs 54 and 55 engaging the contact 23. Due

to the floating mounting of the bridging member 45, the

same will move into the space between the contacts 23 and 24 without interference and due to the provision of the ribs on the tapered surfaces 549 and 51, a relatively large area of contact will be provided between the contacts 23 and 24 and the bridging member 45, regardless of irregularities in the surfaces of the contacts 23 and 24 or curvature thereof which, if only a single flat surface were provided on each tapered surface of the bridging member 45 might result in point or line contacts which would be insufiicient to transmit the relatively high current passing through these contacts during operation of the starting for securing the same in place. The nut 61 also provides a means for engaging the movable contact 31 as shown in FIG. 9, to move the same into engagement with the fixed contact 27.

A compression spring 62 is received in a recess 63 in the Wall 64 of the block 44 and as clearly shown in H6. 5, the spring 62 projects outwardly from the wall of the block 44. In a similar manner, a compression spring 65 is received in a recess 66 in the wall 67 of the block 44 and the spring 65 projects outwardly of the wall 69 of the block 44. As shown in FIGS. 1, 3, 9 and 10 with the block 44 disposed in the recess 11 of the housing 10, the springs 62 and 65 engage the inner surface of the wall 29 of the housing 10 to urge the block 44 in a direction to engage the bridging or switch member 45 with the contacts 23 and 24. In this position, the bridging or switch member 45 is operative to close an electrical circuit between the terminals provided by the screw threaded memhers 14 and 18 and since, such terminals are connected in the starter circuit of the internal combustion engine at this time operation of the normal starter switch will result in normal operation of the starter to start the engine.

A generally rectangular cover plate 66 is provided for closing the recess 11 in the housing 10 and the cover plate 66 as shown in FIG. 8 may be provided with a generally rectangular inwardly projecting portion 67 fitting within the recess 11 and with a peripheral flange 68 overlying the side and end walls of the housing 10 with the cover plate 66 being secured in position by suitable screw threaded fastening means 69 extending therethrough and into the body of the housing 19. This serves to provide a vapor proof assembly which prevents entry of gas or other fumes to the interior of the switch thereby materially reducing fire hazard. Rotatably mounted in the cover plate 66 adjacent the center thereof is a shaft 70 with the outer end thereof projecting outwardly of the plate 66 and with the inner end rotatably received in a recess 71 in the rear wall a 72 of the housing 10, such recess 71 being clearly shown in FIG. 4. When installed, the shaft 70 extends through the aperture 56 in the block 44 and fixed to the shaft 70 within the aperture 56 is a cam 73 which, as shown in FIGS. 1, 3, 9 and 10 is positioned in a manner to engage the cam plate 58 during operation of the shaft 70 and cam 73. In order to operate the cam 73 there maybe provided an actuating arm 74 secured to the outer end of the shaft 70 by a nut 75 or other suitable means and the outer end of the arm 74 may be provided with a suitable fitting 76 for engaging a control wire 77 secured to the fitting 76 by a set screw 78, the control wire 77 extending through a flexible housing 79 to a desired remote position where a suitable finger engaging knob may be provided for actuating the wire 77 to move the :arm 74, shaft 70 and cam 73. The flexible housing 79 may be secured to the mounting bracket 36 by a suitable clamp 80.

The fixed contact 27 and the terminal provided by the screw threaded member 28 may be connected through a suitable conductor 81 to the primary ignition circuit and with the block 44 in the position shown in FIG. 10, the bridging or switch member 45 is in engagement with the contacts 23 and 24 to complete the circuit to the starter of the internal combustion engine to permit operation of the same and also in this position, the movable contact 31 is out of engagement with the fixed contact 27 and upon operation of the starter the internal combustion engine may be started. When it is desired to prevent starting of the internal combustion engine, the control wire 77 may be actuated to move the acting arm 74, shaft 79 and cam 73 in such a manner that the cam 73 moves along the inclined portion 59 of the cam plate 58 to rnove the block 44 to the right as viewed in FIG. 10, against the action of springs 62 and 65 to the position shown in FIG. 9, in which position the bridging or switch member 45 is out of engagement with the contacts 23 and 24 thereby opening the circuit to the starting motor and preventing operation of the same. In this position, it will also be noted that the movable contact 31 is in engagement with the fixed contact 27 thereby grounding the primary ignition circuit which would prevent starting of the motor, even though an auxiliary battery or starting circuit were provided to permit operation of the starter. Consequently, both the starter and ignition circuits are rendered inoperative by actuation of the switch to the position shown in FIG. 9.

With an internal combustion engine utilizing electrical ignition, it is necessary to provide the contacts 27 and 31 to ground the primary circuit of the ignition system in order to stop the engine when the block 44 and contact 45 is moved to the position shown in FIG. 9 which opens the circuit from the battery to ground, since this results in removing the battery from the generator circuit and since the battery provides a relatively large resistance in the generator circuit when connected therein, removal of such battery from the generator circuit and continued opera-tion of the generator results in a greatly increased charging rate or current how in the generator circuit thereby presenting the possibility of damage to the generator or associated electrical equipment. Provision of the contacts 27 and 31 which automatically ground the primary circuit of the ignition system results in immediate stopping of the engine and consequently, the generator upon operation of the switch of this invention and even though the conventional ignition switch may be left on, the engine will not continue operation after actuation of the switch of this invention to open the battery circuit and close the primary ignition circuit. In the normal installation of the master battery or safety switch of this invention the mounting bracket 36 would be secured to the grounded portion of the motor vehicle or internal combustion engine, since the majority of electrical systems found in such installations are of the grounded type. Consequently, it will be seen that the movable contact 31 is grounded through the screw threaded fastening means 34, head 41 and mounting bracket 36 and likewise, the contact 24 is grounded through the screw threaded fastening means 42 and mounting bracket 36; As a result, the fixed contacts 23 and 24, together with the movable contact 45 provide a circuit to ground from the grounded side of the battery with the switch in the position shown in FIG. 10 and in the position shown in FIG. 9, the grounded side of the battery is open while the contacts 27 and 31 serve to ground the primary circuit of the ignition system thereby preventing operation of the engine under these conditions.

In instances where an ungrounded electrical system is utilized, the fixed contacts 23 and 24 are connected in one circuit from the battery to the starter and the screw threaded means 42 is removed to prevent grounding of one side of the starter circuit to the engine or frame through the mounting bracket 36 of the switch which, of course, is still mounted on the frame or engine. In this case, the switch serves to open the circuit directly from the battery to the starter and prevents operation thereof. As before, however, the contacts 27 and 31 serve to ground the primary side of the ignition circuit thereby preventing operation of the engine.

in the case of installation of the switch of this invention on a diesel engine in which electrical ignition is not utilized, the fixed contacts 23 and 24 would be connected in the startercircuit as described above and operation of the switch would close or open such starter circuit. However, in this case, the fixed contact 27 would be connected to the output of the conventional generator or to the generator terminal on the voltage regulator with the result that with the switch of this invention in the position shown in FIG. 9, the contacts 27 and 31 would operate to ground the output of the generator thereby preventing generator burn out or other electrical damage when the switch of this invention was operated to remove the battery from the generator output circuit.

It will be seen that by the above described invention there has been provided a relatively simple, yet highly effective master battery or safety switch for internal combustion engines and due to the vapor proof char-acteristics of the switch the same may also be utilized in boats or other locations where a relatively closed space may give rise to the accumulation of gas or other fumes which would present a fire hazard were the contacts of the switch accessible to such fumes and furthermore, the switch of this invention may be conveniently installed in a convenient location and may be utilized in connection with internal combustion engines having a grounded or ungrounded electrical system and also in connection with diesel engines which do not utilize electrical ignition. The switch of this invention will effectively operate to materially reduce fire hazard, eliminate drain on the battery due to electrical leakage and also serve to prevent unauthorized use of the motor vehicle or internal combustion engine.

It will be obvious to those skilled in the art that various changes may be made in the invention without departing from the spirit and scope thereof and therefore the invention is not limited by that which is shown in the drawings and described in the specification, but only as indicated in the appended claims.

What is claimed is:

l. A master battery switch for internal combustion engines, said switch comprising a generally rectangular housing of insulating material, a generally rectangular recess in said housing, a pair of spaced opposed contacts disposed in said recess at one end, terminals connected to said contacts and extending exteriorly of said housing, a fixed contact disposed in said recess at the opposite end, a terminal connected to said fixed contact and extending exteriorly of said housing a resilient movable contact disposed in said recess and movable into and out of engagement with said fixed contact, a mounting bracket secured to one edge of said housing, means connecting said movable contact and said bracket, removable means connecting said bracket and one contact of said pair, a block of insulating material slidably mounted in said recess, a tapered bridging member loosely attached to said block, the tapered faces of said member being movable between the contacts of said pair to engage the same with a wedging action to complete an electrical circuit through said pair of contacts, each tapered face of said member having spaced ribs for engaging the associated contact at spaced locations, means on said block for engaging said movable contact to move the same into engagement with said fixed contact to complete an electrical circuit, the circuit through said pair of contacts being closed while the circuit through said fixed and movable contact is open and vice versa, compression spring means urging said block in a direct-ion to engage said member with said pair of contacts, said block having a generally rectangular aperture, a cam plate on one wall of said aperture, a cover plate for said recess, a shaft rotatably mounted in said plate and extending through said aperture, a cam on said shafit for engaging said cam plate and an actuating arm on said shaft for actuating said cam to move said block against the action of said spring means to disengage said member from said pair of contacts and move said movable contact into engagement with said fixed contact.

2. A master battery switch for internal combustion engines, said switch comprising a generally rectangular housing of insulating material, a generally rectangular-recess in said housing, a pair of spaced opposed contacts disposed in said recess at one end, terminals connected to said cont-acts and extending exteriorly of said housing, a fixed contact disposed in said recess at the opposite end, a terminal connected to said fixed contact and extending exteriorly of said housing, a resilient movable contact disposed in said recess and movable into and out of engagement with said fixed contact, a mounting bracket secured to one edge of said housing, means connecting said movable contact and said bracket, removable means connecting said bracket and one contact of said pair, a block of insulating material slidably mounted in said recess, a tapered bridging member loosely attached to said block, the tapered faces of said member being movable between the contacts of said pair to engage the same with a wedging action to complete an electrical circuit through said pair of contacts, each tapered face of said member having spaced ribs for engaging the associated contacts at spaced locations, means on said block for engaging said movable contact to move the same into engagement with said fixed contact to complete an electrical circuit, the circuit through said pair of contacts being closed while the circuit through said fixed and movable contact is open and vice versa, compression spring means urging said block in a direction to engage said member with said pair of contacts, said block having a generally rectangular aperture, a cover plate for said recess, a shaft rotatably mounted in said plate and extending through said aperture, a cam on said shaft for engaging a wall of said aperture and an actuating arm on said cam to move said block against the action of said spring means to disengage said member from said pair of contacts and move said movable contact into engagement with said fixed contact.

3. A master battery switch for internal combustion engines, said switch comprising a generally rectangular housing of insulating material, a generally rectangular recess in said housing, a pair of spaced opposed contacts disposed in said recess at one end, terminals connected to said contacts and extending exteriorly of said housing, a fixed contact disposed in said recess at the opposite end, a terminal connected to said fixed contact and extending exteriorly of said housing, a movable cont-act disposed in said recess and movable into and out of engagement with said fixed contact, a mounting bracket secured to one edge of said housing, means connecting said movable contact and said bracket, removable means connecting said bracket and one contact of said pair, a block of insulating material slidably mounted in said recess, a tapered bridging member loosely attached to said block, the tapered faces of said member being movable between the contacts of said pair to engage the same with a wcdgin-g action to complete an electrical circuit through said pair of contacts, each tapered face of said member having spaced ribs for engaging the associated contact at spaced locations, means on said block for engaging said movable contact to move the same into engagement with said fixed contact to complete an electrical circuit, the circuit through said pair of contacts being closed while the circuit through said fixed and movable contact is open and vice versa, compression spring means urging said block to engage said member with said pair of contacts, said block having a generally rectangular aperture, a cover plate for said recess, a shaft rotatably mounted in said plate and extending through said aperture, a cam on said shaft for engaging a Wall of said aperture and an actuating arm on said shaft for actuating said cam to move said block against the action of said spring means to disengage said member from said pair of contacts and move said movable contacts into engagement with said fixed contacts.

4. A master battery safety switch for internal combustion engines, said switch comprising a generally rectangular housing of insulating material, a generall rectangular recess in said housing, a pair of spaced opposed contacts disposed in said recess at one end, terminals connected to said contacts and extending exteriorly of said housing, a

fixed contact disposed in said recess at the opposite end,

a terminal connected to said fixed contact and extending exteriorly of said housing, a movable contact disposed in said recess and movable into and out of engagement with said fixed contact, a mounting bracket secured to one edge of said housing, means connecting said movable con tact and said bracket, removable means connecting said bracket and one contact of said pair, a block of insulating material slidably mounted in said recess, a tapered bridging member loosely attached to said block, the tapered faces of said member being movable between the contacts of said air to en a e the same with a wed ing action to complete an electrical circuit through said pair of contacts, means on said block for engaging said movable contact to move the same into engagement with said fixed contact to complete an electrical circuit, the circuit through said pair of contacts being closed while the circuit through said fixed and movable contacts is open and vice versa, spring means urging said block in a direction to engage said member toward said pair of contacts, said block having a generally rectangular aperture, a cover plate for said recess, a shaft rotatably mounted in said plate and extending through said aperture, a cam on said shaft for engaging a wall of said aperture and an actuating arm on said shaft for cutting said cam to move said block against the action of said spring means to disengage said member from said pair of contacts and move said movable contact into engagement with said fixed contact.

5. A master battery safety switch for internal combustion engines, staid switch comprising a generally rectan- I gular housing of insulating material, a generally rectangular recess in said housing, a pair of spaced opposed contacts disposed in said recess at one end, terminals connected to said contacts and extending exteriorly of said housing, a fixed cont-act disposed in said recess at the opposite end, a terminal connected to said fixed contact and extending exteriorly of said housing, a movable contact disposed in said recess and movable into and out of engagement with said fixed contact, a mounting bracket secured to one edge of said housing, means connecting said movable contact and said bnacket, removable means connecting said bracket and one contact of said pair, a block of insulating material slidably mounted in said recess, a bridging member loosely attached to said block, said member being movable between the contacts of said pair to engage the same to complete an electrical circuit to said pair of contacts, means on said block for engaging said movable contact to move the same into engagement with said fixed contact to complete an electrical circuit, the circuit through said pair of contacts being closed while the circuit through said fixed and movable contact is open and vice versa, spring means urging said block in a direction to engage said member with said pair of contacts, said block having a generally rectangular aperture, a cover plate for said recess, a shaft rotatably mounted in said plate and extending through said aperture, a cam on said shaft for engaging a wall of said aperture and an actuating arm on said shaft for actuating said cam to move said block against the action of said spring means to disengage said member from said pair of contacts and move said movable contact into engagement with said fixed contact.

6. A master battery safety switch for internal combustion engines, said switch comprising a generally rectangular housing of insulating material a generally rectangular recess in said housing, a pair of spaced opposed contacts disposed in said recess at one end, terminals connected to said contacts and extending exteriorly of said housing, a fixed contact disposed in said recess at the opposite end, a terminal connected to said fixed contact and extending exteriorly of said housing, a movable contact disposed in said recess and movable into and out of engagement with said fixed contacts, a mounting bracket secured to said housing, means connecting said movable contact and said bracket, a block of insulating material mounted in said recess, ,a bridging member loosely attached to said block, said member being movable between the contacts of said pair to engage the same to complete an electrical circuit through said pair of contacts, means on said block for engaging said movable contact to move the same into engagement with said fixed contact to complete an electrical circuit, the circuit through said pair of contacts being closed while the circuit through said fixed and movable contact is open and vise versa, spring means urging said block in a direction to engage said member with said pair of contacts, said block having a generally rectangular aperture, .a cover plate for said recess, a shaft rotatably mounted in said plate and extending through said aperture, a cam on said shaft for engaging a wall of said aperture and tan actuating arm on said shaft for actuating said cam to move said block against the action of said spring means to disengage said member from said pair of contacts and move said movable contacts into engagement With said fixed contact.

7. A master battery safety switch for internal combustion engines, said switch comprising a generally rectangular housing of insulating material, a generally rectangular recess in said housing, a pair of spaced opposed contacts disposed in said recess at one end, terminals connected to said contacts and extending exteriorly of said housing, a fixed contact disposed at said recess at the opposite ends, a terminal connected to said fixed contacts and extending exterior-1y of said housing, a movable contact disposed in said recess and movable into and out of engagement with said fixed contact a mounting bracket secured to said housing, means electrically connecting said movable contact and said bracket, a block of insulating material slidably mounted in said recess, a bridging member attached to said block, said member being movable between the contacts of said pair to engage the same to complete an electrical circuit through said pair of contacts, means on said block for engaging said movable contact to move the same into engagement with said fixed contact to complete an electrical circuit, the circuit through said pair of contacts being closed while the circuit through said fixed and movable contact is open and vice versa, spring means urging said block in a direction to engage said member with said pair of contacts, said block having a generally rectangular aperture, a cover plate for said recess, a shaft rotatably mounted in said plate and extending through said aperture, a cam on said shaft for engaging a Wall of said aperture and an actuating arm on said shaft for actuating said cam to move said block against the action of said spring means to disengage said member from said pair of contacts and move said movable contact into engagement with said fixed contact.

8. A master battery satety switch for internal combustion engines, said switch comprising a generally rectangular housing of insulating material, a generally rectangular recess in said housing, a pair of spaced opposed contacts disposed in said recess at one end, terminal connected to said contacts and extending exteriorly of said housing, a fixed contact disposed in said recess at the opposite end, *a terminal connected to said fixed con-tact and extending exterior-1y of said housing, a movable contact disposed in said recess and movable into [and out of engagement with said fixed contact, a mounting bracket secured to said housing, means connecting said movable contact and said mounting bracket, a block of insulating material slidably mounted in said recess, a bridging member attached to said block, said member being movable between the contacts of said pair to engage the same to complete an electrical circuit through said pair of contacts, means on said block for engaging said movable contact to move the same into engagement with said fixed contact to complete an electrical circuit, the circuit through said pair of contacts being closed while the cirunit through said fixed and movable contact is open and vice versa spring means urging said block in a direction to engage said member with said pair of contacts, said block having a generally rectangular aperture, a cover plate for said recess, a shaft rotatably mounted in said plate and extending through said aperture, a cam on said shaft for engaging a wall of said aperture and means for actuating said cam to move said block against the action of said spring means to disengage said member from said pair of contacts and move said movable contact into engagement with said fixed contact.

References Cited in the file of this patent UNITED STATES PATENTS 662,423 Grun'ow Nov. 27, 1900 1,579,559 M011 "Apr. 6, 1926 2,277,671 Williams et a1. Mar. 31, 1942 2,655,583 Souter Oct. 13, 1953 

1. A MASTER BATTERY SWITCH FOR INTERNAL COMBUSTION ENGINES, SAID SWITCH COMPRISING A GENERALLY RECTANGULAR HOUSING OF INSULATING MATERIAL, A GENERALLY RECTANGULAR RECESS IN SAID HOUSING, A PAIR OF SPACED OPPOSED CONTACTS DISPOSED IN SAID RECESS AT ONE END, TERMINALS CONNECTED TO SAID CONTACTS AND EXTENDING EXTERIORLY OF SAID HOUSING, A FIXED CONTACT DISPOSED IN SAID RECESS AT THE OPPOSITE END, A TERMINAL CONNECTED TO SAID FIXED CONTACT AND EXTENDING EXTERIORLY OF SAID HOUSING A RESILIENT MOVABLE CONTACT DISPOSED IN SAID RECESS AND MOVABLE INTO AND OUT OF ENGAGEMENT WITH SAID FIXED CONTACT, A MOUNTING BRACKET SECURED TO ONE EDGE OF SAID HOUSING, MEANS CONNECTING SAID MOVABLE CONTACT AND SAID BRACKET, REMOVABLE MEANS CONNECTING SAID BRACKET AND ONE CONTACT OF SAID PAIR, A BLOCK OF INSULATING MATERIAL SLIDABLY MOUNTED IN SAID RECESS, A TAPERED BRIDGING MEMBER LOOSELY ATTACHED TO SAID BLOCK, THE TAPERED FACES OF SAID MEMBER BEING MOVABLE BETWEEN THE CONTACTS OF SAID PAIR TO ENGAGE THE SAME WITH A WEDGING ACTION TO COMPLETE AN ELECTRICAL CIRCUIT THROUGH SAID PAIR OF CONTACTS, EACH TAPERED FACE OF SAID MEMBER HAVING SPACED RIBS FOR ENGAGING THE ASSOCIATED CONTACT AT SPACED LOCATIONS, MEANS ON SAID BLOCK FOR ENGAGING SAID MOVABLE CONTACT TO MOVE THE SAME INTO ENGAGEMENT WITH SAID FIXED CONTACT TO COMPLETE AN ELECTRICAL CIRCUIT, THE CIRCUIT THROUGH SAID PAIR OF CONTACTS BEING CLOSED WHILE THE CIRCUIT THROUGH SAID FIXED AND MOVABLE CONTACT IS OPEN AND VICE VERSA, COMPRESSION SPRING MEANS URGING SAID BLOCK IN A DIRECTION TO ENGAGE SAID MEMBER WITH SAID PAIR OF CONTACTS, SAID BLOCK HAVING A GENERALLY RECTANGULAR APERTURE, A CAM PLATE ON ONE WALL OF SAID APERTURE, A COVER PLATE FOR SAID RECESS, A SHAFT ROTATABLY MOUNTED IN SAID PLATE AND EXTENDING THROUGH SAID APERTURE, A CAM ON SAID SHAFT FOR ENGAGING SAID CAM PLATE AND AN ACTUATING ARM ON SAID SHAFT FOR ACTUATING SAID CAM TO MOVE SAID BLOCK AGAINST THE ACTION OF SAID SPRING MEANS TO DISENGAGE SAID MEMBER FROM SAID PAIR OF CONTACTS AND MOVE SAID MOVABLE CONTACT INTO ENGAGEMENT WITH SAID FIXED CONTACT. 